Mechanisms of autoimmune encephalitis.

PURPOSE OF REVIEW: To provide an overview of the pathogenic mechanisms involved in autoimmune encephalitides mediated by antibodies against neuronal surface antigens, with a focus on NMDAR and LGI1 encephalitis. RECENT FINDINGS: In antibody-mediated encephalitides, binding of IgG antibodies to neuronal surface antigens results in different pathogenic effects depending on the type of antibody, IgG subclass and epitope specificity. NMDAR IgG1 antibodies cause crosslinking and internalization of the target, synaptic and brain circuitry alterations, as well as alterations of NMDAR expressing oligodendrocytes, suggesting a link with white matter lesions observed in MRI studies. LGI1 IgG4 antibodies, instead, induce neuronal dysfunction by disrupting the interaction with cognate proteins and altering AMPAR-mediated signaling. In-vitro findings have been corroborated by memory and behavioral changes in animal models obtained by passive transfer of patients' antibodies or active immunization. These models have been fundamental to identify targets for innovative therapeutic strategies, aimed at counteracting or preventing antibody effects, such as the use of soluble ephrin-B2, NMDAR modulators (e.g., pregnenolone, SGE-301) or chimeric autoantibody receptor T cells (CAART) in models of NMDAR encephalitis. SUMMARY: A deep understanding of the pathogenic mechanisms underlying antibody-mediated encephalitides is crucial for the development of new therapeutic approaches targeting brain autoimmunity.

Two-year cardio-pulmonary follow-up after severe COVID-19: a prospective study.

Short- and medium-term cardio-pulmonary sequelae after COVID-19 have been extensively studied. However, studies with longer follow-ups are required. This study aims to identify and characterise cardio-pulmonary sequelae, in patients hospitalised for SARS-CoV-2 pneumonia, at 24 months follow-up. This is a prospective, observational cohort study conducted on consecutive patients hospitalised for COVID-19 and acute respiratory failure. Patients were followed up at 24 months with complete pulmonary function tests (PFTs), 6-min walking test and a dyspnoea score (Modified Medical Research Council scale). A subgroup of patients with at least one clinical or functional sign suggestive of increased pulmonary pressures also underwent transthoracic echocardiography (TTE) to evaluate the presence of direct or indirect signs of pulmonary hypertension (PH). Ninety consecutive patients (74% men, median age 59.1 years) were enrolled in the study. In regard to PFTs, carbon monoxide diffusion capacity (DLCO) impairment was observed in 23 cases (26%), in all cases of mild entity. When considering the dyspnoea, 30 (34%) patients showed some degree of breathlessness. Forty patients underwent TTE. No patients had overt PH or chronic thromboembolic PH. However, all patients showed a hyperdynamic state of the right ventricle, and 8 (20%) patients had a decreased acceleration time on pulmonary valve, signs of increased pulmonary vasculature resistances and afterload elevation. At 24-month follow-up after severe COVID-19, DLCO and TTE prove to be the most sensitive tool to detect cardio-pulmonary sequelae. Dyspnoea is still present in about one-third of patients and requires a multidisciplinary approach.

Alzheimer's Disease and Neurosyphilis: Meaningful Commonalities and Differences of Clinical Phenotype and Pathophysiological Biomarkers.

BACKGROUND: Neurosyphilis-associated cognitive and behavioral impairment- historically coined as "general paralysis of the insane"- share clinical and neuroradiological features with the neurodegenerative disease spectrum, in particular Alzheimer's disease (AD). Anatomopathological similarities have been extensively documented, i.e., neuronal loss, fibrillary alterations, and local amyloid-ß deposition. Consequently, accurate classification and timely differential diagnosis may be challenging. OBJECTIVE: To describe clinical, bio-humoral, brain MRI, FDG-PET, and amyloid-PET features in cases of neurosyphilis with an AD-like phenotypical presentation, as well as clinical outcome in terms of response to antibiotic therapy. METHODS: We selected the studies comparing patients with AD and with neurosyphilis associated cognitive impairment, to investigate candidate biomarkers classifying the two neurological diseases. RESULTS: The neuropsychological phenotype of general paralysis, characterized by episodic memory impairment and executive disfunction, substantially mimics clinical AD features. Neuroimaging often shows diffuse or medial temporal cortical atrophy, thus contributing to a high rate of misdiagnosis. Cerebrospinal fluid (CSF)-based analysis may provide supportive diagnostic value, since increased proteins or cells are often found in neurosyphilis, while published data on pathophysiological AD candidate biomarkers are controversial. Finally, psychometric testing using cross-domain cognitive tests, may highlight a wider range of compromised functions in neurosyphilis, involving language, attention, executive function, and spatial ability, which are atypical for AD. CONCLUSION: Neurosyphilis should be considered a potential etiological differential diagnosis of cognitive impairment whenever imaging, neuropsychological or CSF features are atypical for AD, in order to promptly start antibiotic therapy and delay or halt cognitive decline and disease progression.

Pre-existing frontal lobe dysfunction signs as predictors of subsequent neurotoxicity in CAR T cell therapy: insights from a case series.

BACKGROUND: Chimeric Antigen Receptor (CAR) T cell therapies are innovative treatments against hematological malignancies, with increasing therapeutic indications. Despite their great efficacy, these therapies are hampered by high rates of neurotoxicity (immune effector cell-associated neurotoxicity (ICANS)). In the past few years, several risk factors have been associated with ICANS and grouped together in the attempt to build validated models able to predict neurologic complications. However, little is known about pre-existing neurologic conditions possibly related to the development of neurotoxicity. METHODS AND RESULTS: In our case series, including sixteen consecutive patients treated with CAR T cells, we observed that (i) neurotoxicity only occurred in the two patients who presented subtle clinical signs of frontal lobe impairment at baseline and (ii) neurologic manifestations of ICANS consisted of language disturbances and cortical frontal myoclonus, which were both manifestations of a frontal predominant dysfunction. DISCUSSION: Based on our experience, we suggest that a pre-existing frontal lobe impairment, even if at a subclinical level, may eventually drive to ICANS, which in turn shows symptoms compatible with a frontal encephalopathy. It is remarkable that this focal neurotoxicity involved the same CNS regions that were responsible of subtle neurological signs at baseline. Future studies on larger numbers of patients are needed to confirm the possible role of baseline frontal lobe dysfunction as a predictor of ICANS, in order to enhance efforts to safely deliver CAR T cell therapy.

A case of intravascular large B cell lymphoma with brain involvement mimicking progressive multifocal leukoencephalopathy.

Intravascular large B-cell lymphoma (IVLBCL) is a very rare form of extranodal lymphoma, characterized by the proliferation of neoplastic B cells within the lumen of small vessels. Due to its high aggressivity, for years the prognosis had been really poor with only anectodical cases of remission after traditional chemotherapy. More recently, new therapeutic protocols allowed a significant increase in overall survival. It can virtually involve every organ, being skin and central nervous system the most affected. The clinical presentation is often unspecific and insidious; therefore, diagnosis can be challenging. Tissue biopsy, in particular random deep skin biopsy, is the gold standard for definitive diagnosis. We describe the case of a 58-year-old woman with a previous diagnosis of myelofibrosis, who presented with a rapidly progressive neurological deterioration and a brain MRI suggestive of Progressive Multifocal Leukoencephalopathy. Due to the absence of BK and JC viruses in cerebrospinal fluid and the presence of severe myalgias and subcutaneous nodules, a skin and muscle biopsy was performed, allowing diagnosis of IVLBCL. We describe the diagnostic pitfalls of this case, briefly reviewing existing literature about IVLBCL.

Distinct limbic connectivity in left and right benign mesial temporal lobe epilepsy: Evidence from a resting state functional MRI study.

Background: Functional connectivity (FC) studies showed that pharmaco-resistant mesial temporal lobe epilepsy (MTLE) affects not only the limbic system, but also several extra-limbic regions, including areas belonging to resting state networks. Less is known about FC in subjects with benign MTLE (i.e., sensitive to antiseizure medication, bMTLE). Aim and methods: We evaluated FC of hippocampus and amygdala in subjects with bMTLE, distinguished based on the epileptic focus lateralization. We enrolled 19 patients (10 with left and 9 with right bMTLE) and 10 age-matched healthy subjects. Connectivity was investigated at rest by using a seed-based regression analyses approach with four regions of interest (left and right hippocampus, left and right amygdala). Patients were also tested with a neuropsychological battery and their scores were correlated with fMRI data. Results and conclusions: Our study documented an asymmetrical disruption of FC in bMTLE, in relation to the side of the focus. Right subjects only exhibited limited altered connections, while left subjects-who performed worse in verbal memory tests-showed a wide bilateral hypoconnectivity of hippocampus and amygdala with areas belonging to language and memory network. The strength of FC between left limbic areas and language and memory network correlated with better performances in verbal memory tests. Moreover, we observed an increased FC with areas of default mode network, more pronounced in left subjects, a possible attempt to compensate cognitive deficit but without effectiveness.We believe that these findings could help to better characterize bMTLE, in which a dysfunction of limbic connectivity is detectable despite well-controlled epilepsy.

Ictogenesis of viral pneumonia: A comparison between SARS-CoV-2 and H1N1/H3N2.

Several studies reported acute symptomatic seizures as a possible neurological complication of COVID-19 pneumonia. Apart from metabolic imbalances, hypoxia, and fever, other ictogenic mechanisms are likely related to an immune-mediated damage. The same mechanisms are shared by other respiratory viruses. Since neurotropic properties of SARS-CoV-2 have been questioned, we investigated whether SARS-CoV-2 has a similar ictogenic potential to other respiratory non-neurotropic viruses. We conducted a retrospective study identifying 1141 patients with SARS-CoV-2 pneumonia and 146 patients with H1N1/H3N2 pneumonia. We found a similar prevalence of seizures in the two viral pneumonia (1.05% with SARS-CoV-2 vs 2.05% with influenza; p = 0.26). We detailed clinical, electroencephalographic, and neuroradiological features of each patient, together with the hypothesized pathogenesis of seizures. Previous epilepsy or pre-existing predisposing conditions (i.e., Alzheimer's disease, stroke, cerebral neoplasia) were found in one-third of patients that experienced seizures, while two-thirds of patients had seizures without known risk factors other than pneumonia in both groups. The prevalence of pre-existing predisposing conditions and disease severity indexes was similar in SARS-CoV-2 and H1N1/H3N2 pneumonia, thus excluding they could act as potential confounders. Considering all the patients with viral pneumonia together, previous epilepsy (p < 0.001) and the need for ventilatory support (p < 0.001), but not the presence of pre-existing predisposing conditions (p = 0.290), were associated with seizure risk. Our study showed that SARS-CoV-2 and influenza viruses share a similar ictogenic potential. In both these infections, seizures are rare but serious events, and can manifest without pre-existing predisposing conditions, in particular when pneumonia is severe, thus suggesting an interplay between disease severity and host response as a major mechanism of ictogenesis, rather than a virus-specific mechanism.

Prolonged and short epileptiform discharges have an opposite relationship with the sleep-wake cycle in patients with JME: Implications for EEG recording protocols.

In a recent study, we found that during 20.55 ±â€¯1.60 h of artifact-free ambulatory EEG recordings, epileptiform discharges (EDs) longer than 2.68 s occurred exclusively in patients with Juvenile Myoclonic Epilepsy (JME) who experienced seizure recurrence within a year after the EEG. Here we expanded this analysis, exploring whether long EDs (>2.68 s), and short ones, were uniformly distributed during the day. Lastly, we evaluated the temporal distribution of seizure relapses. By Friedman test, we demonstrated that hourly frequencies of both short and long EDs were dependent on the hours of day and sleep-wake cycle factors, with an opposite trend. Short EDs were found mostly during the night (with two peaks at 1 AM and 6 AM), and sleep, dropping at the wake onset (p < 0.001). Conversely, long EDs surged at the wake onset (0.001), remaining frequent during the whole wake period, when compared to sleep (p = 0.002). Of note, this latter pattern mirrored that of seizures, which occurred exclusively during the wake period, and in 9 out of 13 cases at the wake onset. We therefore suggested that short and long EDs could reflect distinct pathophysiological phenomena. Extended wake EEG recordings, possibly including the awakening, could be extremely useful in clinical practice, as well as in further studies, with the ambitious goal of predicting seizure recurrences.

Prolonged epileptic discharges predict seizure recurrence in JME: Insights from prolonged ambulatory EEG.

OBJECTIVE: Markers of seizure recurrence are needed to personalize antiseizure medication (ASM) therapy. In the clinical practice, EEG features are considered to be related to the risk of seizure recurrence for genetic generalized epilepsies (GGE). However, to our knowledge, there are no studies analyzing systematically specific EEG features as indices of ASM efficacy in GGE. In this study, we aimed at identifying EEG indicators of ASM responsiveness in Juvenile Myoclonic Epilepsy (JME), which, among GGE, is characterized by specific electroclinical features. METHODS: We compared the features of prolonged ambulatory EEG (paEEG, 22 h of recording) of JME patients experiencing seizure recurrence within a year ("cases") after EEG recording, with those of patients with sustained seizure freedom for at least 1 year after EEG ("controls"). We included only EEG recordings of patients who had maintained the same ASM regimen (dosage and type) throughout the whole time period from the EEG recording up to the outcome events (which was seizure recurrence for the "cases", or 1-year seizure freedom for "controls"). As predictors, we evaluated the total number, frequency, mean and maximum duration of epileptiform discharges (EDs) and spike density (i.e. total EDs duration/artifact-free EEG duration) recorded during the paEEG. The same indexes were assessed also in standard EEG (stEEG), including activation methods. RESULTS: Both the maximum length and the mean duration of EDs recorded during paEEG significantly differed between cases and controls; when combined in a binary logistic regression model, the maximum length of EDs emerged as the only valid predictor. A cut-off of EDs duration of 2.68 seconds discriminated between cases and controls with a 100% specificity and a 93% sensitivity. The same indexes collected during stEEG lacked both specificity and sensitivity. SIGNIFICANCE: The occurrence of prolonged EDs in EEG recording might represent an indicator of antiepileptic drug failure in JME patients.

Autoimmune limbic encephalitis related to SARS-CoV-2 infection: Case-report and review of the literature.

BACKGROUND: SARS-CoV-2 infection is associated with a wide spectrum of neurological complications, including encephalitis. Most cases showed features consistent with a central nervous system (CNS) cytokine-mediated damage. However, few cases arguing for an autoimmune mechanism have been described, mainly as single reports or sparse in large case series involving other CNS manifestations. In this paper, we described a case of definite autoimmune limbic encephalitis (LE) COVID-19 related and reviewed the existing literature on other reported cases. CASE REPORT: Two weeks after the onset of COVID-19 infection, a 74-year-old woman presented with subacute confusion and focal motor seizures with impaired awareness, starting from left temporal region. Cerebrospinal fluid analysis revealed hyperproteinorrachia. Brain MRI showed bilateral T2/FLAIR hyperintensities in both hippocampi and total body PET/TC scan revealed hypermetabolism in basal ganglia bilaterally. A diagnosis of autoimmune LE was made. Thus, high dose corticosteroids and antiseizure medications were started, with a marked improvement of neurological conditions. LITERATURE REVIEW: We systematically reviewed the literature to identify all well-documented cases of definite autoimmune LE (according to Graus criteria) in patients with COVID-19 infection, identifying other five cases exhibiting a good response to immunomodulating therapy. CONCLUSION: A very limited number of autoimmune LE have been described until now. It is important to monitor neurological symptoms in COVID-19 patients and to consider the possibility of an autoimmune LE, in particular when altered mental status and seizures appear late in the disease course. This allows to promptly start the appropriate treatments and avoid unnecessary delays.

Response to levetiracetam or lamotrigine in subjects with Juvenile Myoclonic Epilepsy previously treated with valproic acid: A single center retrospective study.

BACKGROUND: Valproic acid (VPA) is the most effective medication in juvenile myoclonic epilepsy (JME) but, due to its teratogenic potential, levetiracetam (LEV) and lamotrigine (LTG) are preferred in women of childbearing age. The aim of this study was to compare the effectiveness and tolerability of LEV and LTG monotherapy in patients with a previous good seizure control in VPA monotherapy, in which VPA was withdrawn because of teratogenic potential or adverse drug effects. METHODS: We retrospectively analyzed 65 patients with JME which had been followedup at the Epilepsy Center of Pisa University Hospital, identifying 28 subjects who had been successfully treated with VPA monotherapy and who were shifted to another monotherapy. The second monotherapy was LEV for 14 subjects and LTG for the remaining 14 ones. Drug efficacy was measured in terms of seizure freedom for more than twelve months after reaching the minimum effective or the highest tolerated dose. RESULTS: In terms of seizure control, our analysis showed a significantly better outcome for LEV compared to LTG (14.3% and 71.4% of seizure relapse, respectively, p = 0.006) monotherapy. Such a higher efficacy was confirmed in those subjects with seizure relapse on LTG, who achieved good seizure control after switching to LEV monotherapy (89% of cases). Concerning tolerability, none of the patients reported severe side effects. CONCLUSION: Although obtained in a small case series, our analysis showed a significant better efficacy of LEV compared to LTG in monotherapy, in patients with JME with a good response to VPA, concerning both myoclonic and generalized tonic-clonic seizures.

La legitimación de las medicinas indígenas en México. El ejemplo de Cuetzalan del Progreso (Puebla) / The legitimation of indigenous medicines in Mexico. The example of Cuetzalan del Progreso (Puebla)

La búsqueda de la legitimación de las medicinas tradicionales indígenas se configura como un aspecto particularmente significativo de este movimiento, en el que participan no sólo los indígenas mexicanos, sino también una serie de interlocutores externos con quienes los indígenas negocian con creciente conciencia su nuevo papel en la sociedad mexicana.